Pixel structure of display and method for manufacturing the same

ABSTRACT

A pixel structure of a display including a first substrate, a second substrate, and a liquid crystal (LC) layer disposed therebetween. The pixel structure comprises a plurality of first, second, and third sub-pixels; a plurality of alignment controlling patterns, respectively formed in the first, second and third sub-pixels for controlling alignment direction of LC molecules of the LC layer; a plurality of opaque regions, respectively formed in the first, second, and third sub-pixels, and substantially aligned with the portion of the alignment controlling patterns, so that the alignment controlling patterns are shielded by the substantially corresponded opaque regions having different areas in at least two of the colored sub-pixels.

This application is a divisional application of co-pending applicationSer. No. 11/798,801, filed on May 17, 2007, which claims the benefit ofTaiwan application No. 95135846, filed on Sep. 27, 2006, the contents ofwhich are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pixel structure of display, and moreparticularly, to a pixel structure capable of improving thecolor-shifting of display.

2. Description of the Related Art

Due to the advantages of light weight, thinness depth, small volume, andlower radiation, the liquid crystal displays (LCD) of the flat-paneldisplay whose display effect is much superior to that of a cathode raytube (CRT) display has attracted the public interest in recent years.The consumers also request the preferably images displayed in the LCD.

According to the propagation direction of the ray manner, LCD can becategorized into three types: transmissive type, reflective type, andtransflective type. In the transmissive type LCD, the light source isprovided by a backlight source, and has the advantages of good imagedisplay under the environment having normal light and the dark. However,it is difficult to clearly view or to recognize the image display of thetransmissive type LCD under the sunlight (for example, the user want touse the LCD in outdoors). In the reflective type LCD, ambient light isused as the light source (i.e. no backlight system), so that good imagedisplay is presented in indoors filled with light or outdoors. Also, thepower consumption of the reflective type LCD is lower than that of thetransmissive type LCD. The transflective type LCD, possessing theadvantages of the transmissive type and reflective type LCDs, has beenapplied in the portable electronic products such as cellular phone,personal digital assistant (PDA), etc.

In general, a LCD is assembled by an upper substrate and a lowersubstrate. The space between the upper substrate and the lower substrateis filled with liquid crystal layer having numerous LC molecules. Thepolarization direction of the light passing through the liquid crystallayer is modulated by changing the arrangement direction (i.e. alignmentdirection) of the liquid crystal molecules that is varying with avoltage applied to the pixel electrode. In this way, the polarizedreflected light has the brightness corresponding to the voltage appliedto the pixel electrode. When a voltage is applied to the pixelelectrodes, the arrangement direction of the liquid crystal molecules isto be varied so that the light transmission changes. Thus, the LCD candisplay images with different brightness such as white, black, and thedifferent gray scale, in which including the intermediate of the grayscale. In addition, the liquid crystal molecules of the LCD can becategorized into twisted nematic (TN) mode and vertical alignment (VA)mode. When a voltage is not applied to the pixel electrodes, the TN modeliquid crystal molecules gradually twist layer by layer from one of theliquid crystal molecules of the substrates to another of the liquidcrystal molecules of the substrates having a angle, for example, theuppermost layer of the liquid crystal molecules near the upper substrateto the bottom layer of the liquid crystal molecules near the lowersubstrate having a 90° angle. When a sufficient voltage is applied, theTN mode liquid crystal molecules are to be aligned and parallel to thedirection of the electric field. The VA mode liquid crystal molecules,differently, are aligned and perpendicular to the upper and lowersubstrates when a voltage is not applied, and are twisted a 90° angle tobe aligned and parallel to the upper and lower substrates when asufficient voltage is applied.

For an LCD panel with a large size, such as panel used in a notebook,multi-domains in every pixel of the panel are formed to make highresolution and wide viewing angle of LCD displays.

FIG. 1A and FIG. 1B illustrate the arrangement of multi-domains liquidcrystal molecules in vertical alignment mode of an LCD panel when avoltage is applied and not applied to the panel, respectively. The uppersubstrate structure (i.e. the first substrate structure) 10 and thelower substrate structure (i.e. the second substrate structure) 20 areassembled in parallel and the space between them is filled with a liquidcrystal layer 30 containing numerous liquid crystal molecules 302. Thelower substrate structure 20 includes a substrate (such as a glasssubstrate) 202 on which a thin film transistor (TFT), the metallayer(s), and the insulating layer(s) (those device and layers not beingshown in figures) are formed. A pixel electrode 204 is disposed abovethe insulating layer and is covered with an alignment film 206. Asshown, each of the pixel electrodes 204 is isolated with the spacing208, and the bottoms of the spacings 208 are covered with the alignmentfilm 206. The upper substrate structure 10 includes a first substrate(such as a glass substrate) 102, a transparent electrode (such as ITOelectrode) 104, and an alignment film 106. Also, a protrusion 108 isformed at the upper substrate structure 10 and is covered with thealignment film 106.

As shown in FIG. 1A, when no voltage is applied to the panel, most ofthe liquid crystal molecules 302 are aligned vertically to the pixelelectrode 204. The liquid crystal molecules 302 adjacent to theprotrusion 108 are arranged substantially vertical to the surfaces ofthe protrusion 108, and have an inclination to the pixel electrode 204.Thus, the protrusion 108 provides a pre-tilt angle for the liquidcrystal molecules 302 while no voltage is applied.

As shown in FIG. 1B, when a voltage is applied to the panel, twodifferent domains are formed in a single pixel because of the differentinclinations of the molecules 302 on the left and right sides of theprotrusion 108. To be more specific, the electric field affects the LCmolecules, so as to let the LC molecules adjacent to the left side ofthe protrusion 108 affect the left portion of the liquid crystalmolecules 302 of the pixel, so that the left portion of LC moleculesincline towards the right side. Likewise, the electric field affects theLC molecules, so as to let the LC molecules adjacent to the right sideof the protrusion 108 affect the right portion of the liquid crystalmolecules 302 of the pixel, resulting in the inclination of rightportion of LC molecules towards the left side. FIG. 1A and FIG. 1B showthe example with only two domains in one single pixel. By changing theshape of the protrusion 108, multiple domains can be similarlyimplemented, leading to a wide viewing angle of display. However, theprotrusion 108 can easily cause the problem of light leaking.

Besides formation of the protrusions 108, multiple domains can beachieved by forming the slits at the pixel electrode. Each pixel areacan be divided into several domains by the slits. When a voltage isapplied to the panel, a slanted electric field is generated adjacent tothe edges of the pixel electrode (cut by the slits) so as to cause theinclination of LC molecules near the slits. Those inclined LC moleculesaffect the other LC molecules, so that multi-domains within a pixel andwide viewing angle of display can be obtained.

Referring to FIG. 2A, FIG. 2B and FIG. 2C, for illustrating thesubstrate having TFT structure. FIG. 2A is a cross-sectional view takenalong the line 2A-2A of FIG. 2C illustrating a thin film transistor(TFT) of a second substrate (lower substrate) structure of LCD. FIG. 2Bis a cross-sectional view taken along the line 2B-2B of FIG. 2Cillustrating a storage capacitor (C_(ST)) of a second substratestructure of LCD. FIG. 2C schematically illustrates a single sub-pixelof a multi-domain vertical alignment (MVA) mode of the TFT-LCD. Also,the TFT-LCD shown in FIG. 2C is a “C_(ST) on common” (i.e. storagecapacitors on a common electrode) design.

A conventional TFT-LCD is assembled by a first substrate structure (orupper substrate structure) and a second substrate structure (or lowersubstrate structure). The first substrate structure comprises a numberof transparent pixel electrodes, color filters, and black matrices. Thesecond substrate structure comprises a number of scan lines, data lines,storage capacitors, switching elements (e.g., TFTs), and transparentpixel electrodes. In the TFT-LCD, the data lines perpendicularlyintersect the scan lines to form a number of pixel regions. In afull-color LCD display, each pixel consists of three sub-pixels: red,green, and blue (RGB) sub-pixels, and each sub-pixel is controlled by aTFT. Also, each sub-pixel region is defined by a pair of scan lines andthe corresponding data lines. Each sub-pixel region includes a storagecapacitor C_(ST), a TFT, and a pixel electrode (e.g. a transparent ITO).FIG. 20 can be represented as one of single R, G, or B sub-pixel offull-color displays.

As shown in FIG. 2A (taken along the cross-sectional line 2A-2A of FIG.2C), the second substrate structure comprises a second substrate 202 anda gate electrode 212 is formed (by patterning a first metal layer) onthe second substrate 202. A first insulating layer 213 is formed on thesecond substrate 202 and covers the gate electrode 212. An amorphous-Si(a-Si) layer is formed on the first insulating layer 213 and thenpatterned to form a channel 215. Drain (D) and source (S) are formed onthe first insulating layer 213, by patterning a second metal layer.Next, a passivation layer 216 is formed on the drain (D) and the source(S) and covers the first insulating layer 213. A contact hole 217 isthen formed within the passivation layer 216 to expose the partialsurface of source (S)/drain (D). Finally, a pixel electrode (e.g.transparent ITO) 204 is formed on the passivation layer 216 and fillsthe contact hole 217, so that the pixel electrode 204 is coupled tosource (S)/drain (D).

The scan lines and data lines are respectively formed during thepatterning step of forming the gate electrode 212 and source (S)/drain(D), respectively. Also, the scan lines and data lines are isolated bythe first insulating layer 213.

As shown in FIG. 2B (taken along the cross-sectional line 2B-2B of FIG.2C), a storage capacitor (C_(ST)) includes a common electrode 214 and acapacitor electrode 218. The common electrode 214 and the capacitorelectrode 218 are separated by the first insulating layer 213. Thestorage capacitor (C_(ST)) is formed together with the formation of theTFT. The common electrode 214 is formed after the formation andpatterning of the first metal layer. Likewise, after the formation andpatterning of the second metal layer, the capacitor electrode 218 isformed. The passivation layer 216 covers the capacitor electrode 218 andthe first insulating layer 213. A contact hole 219 is further formedwithin the passivation layer 216. When the pixel electrode 204 is formedover the passivation layer 216, the pixel electrode 204 and thecapacitor electrode 218 are electrically coupled through the contacthole 219. In addition, all of the common electrode 214 of the pixels areconnected to each other, and connected to a common voltage of theTFT-LCD.

As shown in FIG. 2C, each R, G, or B sub-pixel is controlled by the dataline (DL) and the scan line (SL). Each sub-pixel comprises a thin filmtransistor (TFT) 27, a pixel electrode (PE) 204, and a common electrode(V_(COM)) of the storage capacitor. The common electrode (V_(COM)) ofFIG. 2C is the patterned first metal layer (denoted as 214) of FIG. 2B.The patterned second metal layer is as capacitor electrode 218 and isformed above the common electrode (V_(COM)), and the pixel electrode 204on the top is electrically connected to the capacitor electrode 218through the contact hole 219. Also, several slits 220 are formed in thepixel electrode 204 to acquire a result of the multi-domains and wideviewing angle. Furthermore, a protrusion 108 formed on the firstsubstrate structure 10 is also demonstrated in FIG. 2C, for being usedas another structure to achieve multi-domains and wide viewing angleeffect.

Although multi-domains and wide viewing angle effect of display can beachieved by forming the protrusions 108 (as shown in FIG. 1A and FIG.1B) or/and the slits 220 (as shown in FIG. 2C), the protrusions 108or/and the slits 220 can cause the considerable problem of light leakagein the dark-state. Typically, the conventional display is not completelydark when it is in a dark-state. Also, the differences of light-leakingamounts of the RGB sub-pixels cause the color-shifting problem. Theconventional display usually occurs a color of dark with a tendency ofblue (not completely dark) when it is in a dark-state.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a pixelstructure of display having an opaque region to shield the alignmentcontrolling patterns, so that the color of display can be effectivelyimproved.

According the aspect of the present invention, a pixel structure of adisplay including a first substrate, a second substrate, and a liquidcrystal (LC) layer disposed therebetween. The pixel structure comprisesa plurality of first, second, and third sub-pixels; a plurality ofalignment controlling patterns formed in the first, second and thirdsub-pixels; and a plurality of opaque regions formed in the first,second, and third sub-pixels, and substantially aligned with at leastportion of the alignment controlling patterns, so that the opaqueregions are substantially overlapped with at least portion of thealignment controlling patterns having a shielding area in at least twoof the colored sub-pixels is substantially different from each other.

According the aspect of the present invention, a method formanufacturing a pixel structure of a display including a firstsubstrate, a second substrate, and a liquid crystal (LC) layerinterposed therebetween is provided. The method comprises: forming aplurality of first, second, and third sub-pixels; forming a plurality ofalignment controlling patterns in the first, second, and thirdsub-pixels; forming a plurality of opaque regions in the first, second,and third sub-pixels, and substantially aligned with at least portion ofthe alignment controlling patterns, so that the opaque regions aresubstantially overlapped with at least portion of the alignmentcontrolling patterns having a shielding area in at least two of thecolored sub-pixels is substantially different from each other.

According the aspect of the present invention, a method formanufacturing a display is provided, and the method comprises: providinga first substrate structure and a second substrate structure; forming aplurality of first, second, and third sub-pixels on the first substratestructure and the second substrate structure; forming a plurality ofalignment controlling patterns in the first, second, and thirdsub-pixels; forming a plurality of opaque regions in the first, second,and third sub-pixels, and substantially aligned with at least portion ofthe alignment controlling patterns, so that the opaque regions aresubstantially overlapped with at least portion of the alignmentcontrolling patterns having a shielding area in at least two of thecolored sub-pixels is substantially different from each other; andassembling a liquid crystal (LC) layer between the first substratestructure and the second substrate structure.

Other objects, features, and advantages of the present invention willbecome apparent from the following detailed description of the preferredbut non-limiting embodiments. The following description is made withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B illustrate the arrangement of multi-domain liquidcrystal molecules in vertical alignment mode of an LCD panel when avoltage is applied and not applied to the panel, respectively.

FIG. 2A is a cross-sectional view taken along the line 2A-2A of FIG. 2Cillustrating a thin film transistor (TFT) of a second substratestructure of LCD.

FIG. 2B is a cross-sectional view taken along the line 2B-2B of FIG. 2Cillustrating a storage capacitor (C_(ST)) of a second substratestructure of LCD.

FIG. 2C schematically illustrates a single sub-pixel of a multi-domainvertical alignment (MVA) mode TFT-LCD.

FIG. 3 illustrates the protrusions formed in a single sub-pixel of thedisplay according to the first embodiment of the present invention.

FIG. 4A˜FIG. 4B are cross-sectional views taken along the line 4L-4L ofFIG. 3, wherein a black matrix and a metal are used as opaque regionsfor shielding the protrusions, respectively.

FIG. 5A˜FIG. 5B are top views illustrating the black matrix of FIG. 4Acovering half area of protrusions and all of protrusions, respectively.

FIG. 6 illustrates the slits formed in a single sub-pixel of the TFT-LCDaccording to the second embodiment of the present invention.

FIG. 7A˜FIG. 7B are cross-sectional views taken along the line 7L-7L ofFIG. 6, wherein a black matrix and a metal are used as opaque regions,respectively.

FIG. 8A˜FIG. 8B are top views illustrating the black matrix of FIG. 7Acovering half slits and all of slits, respectively.

FIG. 9 illustrates the protrusions and slits formed in a singlesub-pixel of the TFT-LCD according to the third embodiment of thepresent invention.

FIG. 10A˜FIG. 10B are cross-sectional views taken along the line 10L-10Lof FIG. 9, wherein a black matrix and a metal are used as opaqueregions, respectively.

FIG. 11A˜FIG. 11B are top views illustrating the black matrix of FIG.10A covering half area and all of alignment controlling pattern(including slits and protrusions), respectively.

FIG. 12 illustrates each pixel of the TFT-LCD having four sub-pixelsaccording to the fourth embodiment of the present invention, wherein theprotrusions are formed in the sub-pixels.

FIG. 13 is a top view illustrating a black matrix formed in the fourthsub-pixel of FIG. 12.

FIG. 14 is a chromaticity diagram showing color performance of displayaccording to the shielding experimental results of the presentinvention.

FIG. 15 is a chromaticity diagram showing color performance of a displayaccording to one of the shielding experimental results of the presentinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

A pixel structure capable of improving the color of display, inparticular, improving the dark-state color of display, is provided inthe present invention. In the present invention, the alignmentcontrolling patterns (i.e. the objects causing light-leaking problem),such as protrusions and/or slits formed on the first and/or secondsubstrates, are adequately shielded by opaque regions. The opaqueregions could be formed by parts of black matrix (such as photo-resist,or the like), metals, or others, or combinations thereof. The lightleakage amount of each sub-pixel is reduced by the shielding of theopaque region. The alignment controlling patterns in at least portion ofthe sub-pixels are optionally shielded by the corresponding opaqueregions having different areas, so that the light-leaking amounts in thesub-pixels (such as R, G, B, or the like) differ from each other. Thus,the conventional color-shifting problem (caused by the differences oflight-leaking amounts of the RGB sub-pixels) can be effectively solved,particularly when the display is in the dark-state.

A pixel structure of a display includes a first substrate, a secondsubstrate, and a liquid crystal (LC) layer interposed therebetween. Thepixel structure comprises a plurality of first, second, and thirdsub-pixels; a plurality of alignment controlling patterns formed in thefirst, second and third sub-pixels for controlling alignment directionof LC molecules; a plurality of opaque regions formed in the first,second, and third sub-pixels, and substantially aligned with at leastportion of the alignment controlling patterns. The alignment controllingpatterns of at least two different colored sub-pixels of the sub-pixelsare shielded by the corresponded opaque regions having different areas.According to the embodiments of the present invention, the first,second, and third sub-pixels adapted to emit red, green, and blue colorsof light are as the exemplification of the present invention. However,the present invention is not limited herein, other colors assigned toareas on the commission international de I, eclairage (CIE) chromaticitydiagram, such as purple, yellow-green, orange-red, red-brown, yellow,indigo blue, or the other colors, can be the light colors emitted fromthe sub-pixels.

Several embodiments of the present invention, including the first,second, third, and four embodiments, are disclosed according todifferent types of alignment controlling patterns. However, theembodiments disclosed herein merely illustrate the present invention,and the scope of the present invention is not limited thereto. The pixelstructures of the embodiments of the present invention are applied to athin film transistor-liquid crystal display (TFT-LCD) panel forillustration. Referring to FIG. 1A˜FIG. 1B FIG. 2A˜FIG. 2C, which depictthe TFT-LCD panel in details. Also, the same components depicted in theembodiments of the present invention are denoted by the same referencenumbers. Additionally, in order to avoid obscuring the invention, thedrawings used for illustrating the embodiments of the present inventiononly show the major characteristic parts including the alignmentcontrolling pattern and the corresponding opaque region within a singlesub-pixel (R, G, or B sub-pixels). Accordingly, the specification andthe drawings are to be regarded in an illustrative sense rather than ina restrictive sense.

First Embodiment

In the first embodiment of the present invention, the upper substratestructure (i.e. the first substrate structure) has the protrusions, andthe protrusions are as an alignment controlling pattern in the TFT-LCD.

Referring to FIG. 3, FIG. 4A˜FIG. 4B and FIG. 5A˜FIG. 5B. FIG. 3illustrates the protrusions formed in a single sub-pixel of the TFT-LCDaccording to the first embodiment of the present invention. FIG. 4A˜FIG.4B are cross-sectional views taken along the line 4L-4L of FIG. 3,wherein a black matrix and a metal are used as opaque regions to shieldthe protrusions, respectively. FIG. 5A˜FIG. 5B are top viewsillustrating the black matrix of FIG. 4A covering half area ofprotrusions and all of protrusions, respectively.

As shown in FIG. 3, each sub-pixel (R, G, or B sub-pixels), controlledby a data line (DL) and a scan line (SL), and comprises a thin filmtransistor (TFT) 27 and a pixel electrode (PE) 204. A storage capacitor(CST) includes a common electrode (VCOM) 214 and/or at least one of acapacitor electrode 218 and a portion of the pixel electrode 204. Byexample, the capacitor electrode 218 (formed by patterning the secondmetal layer) is positioned above the common electrode (VCOM) 214, andthe most upper pixel electrode 204 disposed on the capacitor electrode218 and is electrically connected to the capacitor electrode 218 throughthe contact hole 219. Also, the upper substrate structure (i.e. thefirst substrate structure) has several protrusions 308, and theprotrusions 308 are as the alignment controlling pattern herein. Whenthe upper substrate structure is assembled to the lower substratestructure, the purposes of multi-domains and wide viewing angle effectcan bed achieved due to the existence of those protrusions 308. FIG. 3also shows a single sub-pixel with the positions of protrusions 308.

In the present embodiment of the invention, at least one of black matrixand metal used as the opaque regions are positioned corresponding to theprotrusions 308 to shield all or part of light leakages within asub-pixel. As shown in FIG. 4A and FIG. 4B, the first substratestructure (i.e. the upper substrate structure) 10 and the secondsubstrate structure (i.e. the lower substrate structure) 20 areassembled and the space between them is filled with a liquid crystallayer 30 containing numerous liquid crystal molecules 302. The secondsubstrate structure 20 includes a second substrate 202 on which a thinfilm transistor (TFT) (not shown) and passivation layer 203 are formed.A pixel electrode 204 is disposed above the passivation layer 203 and iscovered with an alignment film 206. The first substrate structure 10includes a first substrate 102, a color filter layer 103, a transparentelectrode 104, the protrusion 308 and an alignment film 106. Also, thesurface of the protrusion 308 is covered by the alignment film 106. Theprotrusion 308 provides a pre-tilt angle for the liquid crystalmolecules 302 when no voltage is applied to the first substratestructure 10 and the second substrate structure 20.

In FIG. 4A, the first substrate structure 10 further includes a blackmatrix 408, and part of the black matrix 408 is used as the opaqueregion to shield all or part of the protrusion 308. In FIG. 4B, themetal layer 418 of the second substrate structure is used as the opaqueregion to shield all or part of the protrusion 308.

FIG. 5A˜FIG. 5B are top views illustrating the black matrixes 408 ofFIG. 4A, wherein the black matrix 408 of FIG. 5A covers half area of theprotrusions 308, and the black matrix 408 of FIG. 5B covers all of theprotrusions 308. It is, of course, understood by people in the relatedart that the patterns of the black matrix 408 are not limited to thepatterns of FIG. 5A and FIG. 5B. Practically, the patterns of the blackmatrix 408, patterns of the protrusions 308, and percentage of theprotrusions 308 covered by the black matrix 408 are determined accordingto the requirements of the applications.

Second Embodiment

In the second embodiment of the present invention, several slits areformed on the second substrate structure (i.e. the lower substratestructure) as an alignment controlling pattern in the TFT-LCD.

Referring to FIG. 6, FIG. 7A˜FIG. 7B and FIG. 8A˜FIG. 8B. FIG. 6illustrates the slits formed in a single sub-pixel of the TFT-LCDaccording to the second embodiment of the present invention. FIG.7A˜FIG. 7B are cross-sectional views taken along the line 7L-7L of FIG.6, wherein a black matrix and a metal are used as opaque regions,respectively. FIG. 8A˜FIG. 8B are top views illustrating the blackmatrix of FIG. 7A covering half slits and all of slits, respectively.

As shown in FIG. 6, each sub-pixel (R, G or B sub-pixel) controlled by adata line and a scan line comprises a thin film transistor (TFT) 27 anda pixel electrode (PE) 204. A storage capacitor (CST) includes a commonelectrode (VCOM) 214 and/or at least one of a capacitor electrode 218and a portion of the pixel electrode 204. By example, the capacitorelectrode 218 (formed by patterning the second metal layer) ispositioned above the common electrode (VCOM) 214, and the most upperpixel electrode 204 disposed on the capacitor electrode 218 and iselectrically connected to the capacitor electrode 218 through thecontact hole 219. Also, several slits 608 are formed on the secondsubstrate structure (i.e. lower substrate structure) as the alignmentcontrolling pattern. The purposes of multi-domains and wide viewingangle effect can bed achieved due to the existence of those slits 608.FIG. 6 also shows the positions of slits 608 within a single sub-pixel.

In the present embodiment of the invention, at least one of black matrixand metal used as the opaque regions are positioned corresponding to theslits 608 to shield all or part of light leakages within a sub-pixel. Asshown in FIG. 7A and FIG. 7B, the first substrate structure (i.e. theupper substrate structure) 10 and the second substrate structure (i.e.the lower substrate structure) 20 are assembled and the space betweenthem is filled with a liquid crystal layer 30 containing numerous liquidcrystal molecules 302. The second substrate structure 20 includes asecond substrate 202 on which a thin film transistor (TFT) (not shown)and passivation layer 203 are formed. A pixel electrode 204 is disposedabove the passivation layer 203 and is covered with an alignment film206. Each sub-pixel area can be divided into several domains by theslits 608 of the pixel electrode 204. When a voltage is applied to thesubstrates, a slanted electric field is generated adjacent to the edgesof the pixel electrode (cut by the slits 608) 204 so as to cause theinclination and/or twist of LC molecules adjacent to the slits 608.Those inclined and/or twisted LC molecules affect the other LCmolecules, so that multi-domains within a pixel and wide viewing angleof display can be obtained. The first substrate structure 10 includes afirst substrate 102, a color filter layer 103, a transparent electrode104, the protrusion 308, and an alignment film 106.

In FIG. 7A, the first substrate structure 10 further includes a blackmatrix 708, and part of the black matrix 708 is used as the opaqueregion to shield all or part of the slit 608. In FIG. 7B, the metallayer 718 of the second substrate structure 20 is used as the opaqueregion to shield all or part of the slit 608.

FIG. 8A˜FIG. 8B are top views illustrating the black matrixes 708 ofFIG. 7A, wherein the black matrix 708 of FIG. 8A covers half area of theslit 608, and the black matrix 708 of FIG. 7B covers all of the slits608. It is, of course, understood by people in the related art that thepatterns of the black matrix 708 are not limited to the patternsdepicted in FIG. 8A and FIG. 8B. Practically, the patterns of the blackmatrix 708, patterns of the slits 608, and percentage of the slits 608covered by the black matrix 708 are determined according to therequirements of the applications.

Third Embodiment

In the third embodiment of the present invention, the protrusions formedon the first substrate structure (i.e. the upper substrate structure)and several slits formed on the second substrate structure (i.e. thelower substrate structure) are used as the alignment controlling patternin the TFT-LCD.

Referring to FIG. 9, FIG. 10A˜FIG. 10B and FIG. 11A˜FIG. 11B. FIG. 9illustrates the protrusions and slits formed in a single sub-pixel ofthe TFT-LCD according to the third embodiment of the present invention.FIG. 10A˜FIG. 10B are cross-sectional views taken along the line 10L-10Lof FIG. 9, wherein a black matrix and a metal are used as opaqueregions, respectively. FIG. 11A˜FIG. 11B are top views illustrating theblack matrix of FIG. 10A covering half area and all of alignmentcontrolling pattern (including slits and protrusions), respectively.

As shown in FIG. 9, each sub-pixel (R, G or B sub-pixel) controlled by adata line and a scan line comprises a thin film transistor (TFT) 27 anda pixel electrode (PE) 204. A storage capacitor (CST) includes a commonelectrode (VCOM) 214 and/or at least one of a capacitor electrode 218and a portion of the pixel electrode 204. By example, the capacitorelectrode 218 (formed by patterning the second metal layer) ispositioned above the common electrode (VCOM) 214, and the most upperpixel electrode 204 disposed on the capacitor electrode 218 and iselectrically connected to the capacitor electrode 218 through thecontact hole 219. Also, several protrusions 808 and slits 908 of thepixel electrode 204 are respectively formed on at least one of the firstand second substrate structure to be the alignment controlling pattern.The purposes of multi-domains and wide viewing angle effect can bedachieved due to the existence of those protrusions 808 and slits 908.FIG. 9 clearly shows the positions of protrusions 808 and slits 908within a single sub-pixel according to the third embodiment of thepresent invention.

In the present embodiment of the invention, at least one of black matrixand metal used as the opaque regions are positioned corresponding to theprotrusions 808 and the slits 908 for completely or partially shieldingthe light leakages within a sub-pixel. As shown in FIG. 10A and FIG.10B, the first substrate structure (i.e. the upper substrate structure)10 and the second substrate structure (i.e. the lower substratestructure) 20 are assembled in parallel and the space between them isfilled with a liquid crystal layer 30 containing numerous liquid crystalmolecules 302. The first substrate structure 10 includes a firstsubstrate 102, a color filter layer 103, a transparent electrode 104,and an alignment film 106. Also, the protrusions 808 are formed on thetransparent electrode 104. The second substrate structure 20 includes asecond substrate 202, a thin film transistor (TFT) (not shown), apassivation layer 203, a pixel electrode 204, and an alignment film 206.Also, several slits 908 are formed on the pixel electrode 204 to divideeach sub-pixel area into several domains.

In FIG. 10A, the first substrate structure 10 further includes a blackmatrix 918, and part of the black matrix 918 is used as the opaqueregion to shield all or part of the alignment controlling pattern(including the protrusions 808 and the slits 908). In FIG. 10B, themetal layer 928 of the second substrate structure 20 is used as theopaque region to shield all or part of the protrusions 808 and the slits908.

FIG. 11A˜FIG. 11B are top views illustrating the black matrixes 918 ofFIG. 10A, wherein the black matrix 918 of FIG. 11A covers half area ofthe alignment controlling pattern (including the protrusions 808 and theslits 908), and the black matrix 918 of FIG. 11B covers all ofprotrusions 808 and the slits 908. It is, of course, understood bypeople in the related art that the patterns of the black matrix 918 arenot limited to the patterns of FIG. 11A and FIG. 11B. Practically, thepatterns of the black matrix 918, the patterns of the alignmentcontrolling pattern, and percentage of the alignment controlling pattern(including the protrusions 808 and the slits 908) covered by the blackmatrix 918 are determined according to the requirements of theapplications.

Fourth Embodiment

FIG. 12 illustrates each pixel of the TFT-LCD having four sub-pixelsaccording to the fourth embodiment of the present invention, wherein theprotrusions are formed in the sub-pixels. Besides the first, second, andthird sub-pixels (ex. R, G, and B sub-pixels), a fourth sub-pixel can befurther incorporated with those sub-pixels to increase a variety ofpixel colors. The light emitted from the fourth sub-pixel could becolorless, red, green, blue, or other colors assigned to areas on theCIE Chromaticity Diagram (such as purple, yellow-green, orange-red,red-brown, yellow, indigo blue, and etc.). Although four sub-pixels aretaken as illustration in the fourth embodiment of the present invention,the present invention is not limited herein. More than four sub-pixels,such as six or eight sub-pixels could be incorporated in a single pixel.Also, the protrusions are constructed in the four sub-pixels to be thealignment controlling pattern in the TFT-LCD according to the fourthembodiment, but not-limited it, the other typed of the alignmentcontrolling pattern can to used, such as the slits, the slits and theprotrusions.

As shown in FIG. 12, each pixel includes the first sub-pixel 1001, thesecond sub-pixel 1002, the third sub-pixel 1003, and the fourthsub-pixel 1004. The alignment controlling pattern (such as formed by theprotrusions 308) in each of the sub-pixel areas 1001-1004 issubstantially identical to that in the first embodiment (see FIG. 3). Inthe present embodiment of the invention, at least one of black matrixand metal can be used as the opaque regions to shield all or part ofprotrusions 308. For example, if the colors emitted from the firstsub-pixel 1001, the second sub-pixel 1002, and the third sub-pixel 1003are red, green, and blue, the pattern of the opaque region shown in FIG.5A or FIG. 5B is substantially similar to the pattern of the blackmatrix of the first embodiment of the present invention (to shield allor part of the protrusion 308). If the light emitted from the fourthsub-pixel 1004 is colorless, the pattern of opaque region could bedesigned as a frame-shape is surrounding the fourth sub-pixel 1004; forexample, the opaque region could be a black matrix following the scanline and data line, or a black matrix corresponding to the color filterlayer. FIG. 13 is a top view illustrating a black matrix formed in thefourth sub-pixel of FIG. 12. As shown in FIG. 13, the black matrix 1008formed in the fourth sub-pixel 1004 functions as an opaque region, andthe pattern of the black matrix 1008 is corresponding to the scan lineand data line. The protrusions 308 in the fourth sub-pixel 1004 are notshielded by the black matrix 1008. It is, of course, understood bypeople in the related art that the patterns of the black matrix are notlimited to the pattern of FIG. 12. If fourth sub-pixel 1004 is othercolor and incorporated in the pixel structure, the pattern of the blackmatrix could be illustrated in at least one of the first, second, andthird embodiments.

Pixel Structure of Display and Shielding Experiments

The shielding experiments are conducted by constructing several pixelstructures of display, and each of these pixel structures comprises:

(1) a plurality of first, second, and third sub-pixels, respectivelyemitting red, green, and blue colors of light;

(2) a plurality of alignment controlling patterns, respectively formedin the first, second and third sub-pixels so as to control the alignmentdirections of the LC molecules; for example: the alignment controllingpatterns could be the protrusions as demonstrated in the firstembodiment of the present invention, or the slits as demonstrated in thesecond embodiment of the present invention, or the protrusions togetherwith the slits as demonstrated in the third embodiment of the presentinvention;

(3) a plurality of opaque regions, respectively formed in the first,second, and third sub-pixels and corresponding to the alignmentcontrolling patterns, so that the alignment controlling patterns of atleast two of sub-pixels are shielded by the opaque regions havingdifferent areas. In other words, in the shielding experiments, at leasttwo groups of sub-pixels adapted to emit different colors of the RGBsub-pixels are selected, and the alignment controlling patterns thereofare covered by the opaque regions having different areas.

FIG. 14 is a chromaticity diagram showing color performance of displayaccording to the shielding experimental results of the presentinvention.

♦, experimental result showing the display in a white state of thechromaticity diagram when no opaque region (OR) is constructed withinthe sub-pixels, (x, y)=(0.266, 0.28).

*, experimental result showing the display in a dark state of thechromaticity diagram when no opaque region is constructed within thesub-pixels, (x, y)=(0.251, 0.24).

▴, experimental result showing the display in a dark state of thechromaticity diagram when all the alignment controlling patterns in theR sub-pixels are completely shielded by the opaque regions, (x,y)=(0.232, 0.237).

▪, experimental result showing the display in a dark state of thechromaticity diagram when all the alignment controlling patterns in theG sub-pixels are completely shielded by the opaque regions, (x,y)=(0.247, 0.196).

, experimental result showing the display in a dark state of thechromaticity diagram when all the alignment controlling patterns in theB sub-pixels are completely shielded by the opaque regions, (x,y)=(0.291, 0.313).

⋄, experimental result showing the display in a dark state of thechromaticity diagram when all the alignment controlling patterns in theR, G and B sub-pixels are completely shielded by the opaque regions, (x,y)=(0.267, 0.255).

Δ, experimental result showing the display in a dark state of thechromaticity diagram when half area of the alignment controllingpatterns in the R sub-pixels are shielded by the opaque regions, (x,y)=(0.242, 0.240).

□, experimental result showing the display in a dark state of thechromaticity diagram when half area of the alignment controllingpatterns in the G sub-pixels are shielded by the opaque regions, (x,y)=(0.250, 0.220).

∘, experimental result showing the display in a dark state of thechromaticity diagram when half area of the alignment controllingpatterns in the B sub-pixels are shielded by the opaque regions, (x,y)=(0.268, 0.272).

The results of FIG. 14 have indicated that:

(1) When the alignment controlling patterns in the R sub-pixels areshielded by the opaque regions, the chromatic coordinates (i.e. thechromaticity diagram) in the dark state are positioned at left sides ofthe diagram, and are trend toward to left of the diagram. Moreover, theposition representing the R sub-pixels being are completely shielded(i.e. ▴) is more left than being half shielded (i.e. Δ).

(2) when the alignment controlling patterns in the G sub-pixels areshielded by the opaque regions, the chromatic coordinates in the darkstate approach to the left-down of the diagram, and are trend toward toleft-down of the diagram. Moreover, the position representing the Gsub-pixels being are completely shielded (i.e. ▪) is more left-down thanbeing half shielded (i.e. □).

(3) when the alignment controlling patterns in the B sub-pixels areshielded by the opaque regions, the chromatic coordinates in the darkstate approach to the right-upper of the diagram, and are trend towardto left-down of the diagram. Moreover, the position representing the Gsub-pixels being are completely shielded (i.e. ) is more right-upperthan being half shielded (i.e. ∘).

Therefore, by adjusting the shield conditions (ex: proportions and/orslits) of the alignment controlling patterns in the R, G and Bsub-pixels, the chromatic coordinate of the dark-state display can becontrolled and moved to the expected position according to the practicalapplication. Thus, the color of display, especially in the dark state,can be effectively improved by the present invention.

FIG. 15 is a chromaticity diagram showing color performance of a displayaccording to one of the shielding experimental results of the presentinvention. In FIG. 15, ▴ and * are the experimental results showing thedisplay in the white and dark states when no opaque region (OR) isconstructed within the sub-pixels. ▴ is the experimental result showingthe display in a dark state when about 100% area of the alignmentcontrolling patterns in the R sub-pixels, about 50% area of thealignment controlling patterns in the G sub-pixels, and about 90% areaof the alignment controlling patterns in the G sub-pixels are shieldedby the opaque regions, respectively. The results of FIG. 15 indicatethat the positions of ▴ and ♦ substantially overlapped or substantiallymatched together, so that the opaque regions provided by the presentinvention effectively improve the color of LCD display in the darkstate.

Moreover, it is noted that light can penetrate the protrusions. Althoughcovering the protrusions could reduce the light leakage in the darkstate and increase the color contrast, the brightness is decreased. Ingeneral, the brightness value of the G sub-pixel is highest, and thebrightness value of B sub-pixel is lowest. In other words, the Bsub-pixel provides the least of the overall brightness value. In thepractical application, substantially smaller proportion of theprotrusions in the G sub-pixels and substantially greater or allproportion of the protrusions in the B sub-pixels should be shielded, soas to maintain the brightness at a certain value in the consideration ofthe brightness issue and to improve the colors in the dark status. Inother words, the majority of the protrusions or the entire protrusionsin some color subs-pixels (such as blue sub-pixels or likes) should beshield for the lower supply value of the brightness. As shown in FIG.14, the color of the display in a dark state when about 50% areas of thealignment controlling patterns in the B sub-pixels are shielded by theopaque regions (i.e. ∘) is not substantially identical but still closeto the color of the display in a white state when no opaque region (OR)is constructed within the sub-pixels (i.e. ♦).

According to the results of shielding experiments, the color of LCDdisplay, especially in the dark state, can be improved by any one of theconditions listed below.

(1) The area of the alignment controlling patterns in the B sub-pixelsshielded by the opaque regions is substantially greater than that in theR sub-pixels shielded by the opaque regions.

(2) The area of the alignment controlling patterns in the B sub-pixelsshielded by the opaque regions is substantially greater than that in theG sub-pixels shielded by the opaque regions.

(3) The area of the alignment controlling patterns in the B sub-pixelsis shielded by the opaque regions, preferred, the area in the Bsub-pixels is about 50% to about 100%

(4) The area of the alignment controlling patterns in the G sub-pixelsis shielded by the opaque regions, preferred, the area in the Gsub-pixels is substantially equal to or substantially smaller than 50%.

(5) The area of the alignment controlling patterns in the R sub-pixelsis shielded by the opaque regions, preferred, the area in the Rsub-pixels is substantially equal to or substantially smaller than 50%.

Additionally, there is no limitation of the TFT types when the presentinvention is applied to a TFT-LCD. The TFT type of the display comprisesa bottom gate structure, a top gate structure, or others. The TFT typeof the display could be a n-type TFT, p-type TFT, or a combinationthereof, manufacturing by the polysilicon, amorphous silicon,micro-crystalline silicon mono-crystalline silicon process, other'sprocess, or combinations thereof. Also, the first and second substratesof the display can be made of various materials, for example, at leastone of them could be the transparent substrates (such as glass, quartz,or the like), or the opaque substrates (such as ceramic, silicon, or thelike), or the flexible plastic substrates (such as robber, polyester,polyamide, polyolefines poly-oxides, or the likes).

Moreover, the position of color filter 103 is not limited in the presentinvention although it is set in the first substrate structure in thefirst to fourth embodiments. The present invention is also applicable toa COA (color filter on array) type of the LCD (or known as AOC (array oncolor filter) type of the LCD, which means the color filter is disposedon the second substrate structure (having one or more TFTs in one pixel)to increase the alignment accuracy between the black matrix and the datalines.

It is noted that the present invention is also applicable to differenttypes of displays, including transmissive type, reflective type, andtransflective type display. If the pixel electrode on the secondsubstrate structure is made of transparent material includingtransparent metal oxide (such as indium zinc oxide, indium tin oxide,aluminum zinc oxide, cadmium zinc oxide, the likes, or combinationsthereof), the display could be a transmissive type display, and could beone of the applicable displays of the present invention. If the pixelelectrode on the second substrate structure is made of reflectivematerial including metal (such as titanium, aluminum, chromium,tantalum, gold, silver, copper, iron, neodymium, molybdenum, and thelikes), alloy, or combinations thereof, the display could be areflective type display, and could be one of the applicable displays ofthe present invention. If the pixel electrode on the second substratestructure is made of the transparent and reflective materials (i.e. aportion of pixel electrode made of the transparent material and theother portions of pixel electrode made of the reflective material), thedisplay could be a transflective type display, and could be one of theapplicable displays of the present invention. Accordingly, the first,second, and third sub-pixels illustrated in the above-mentionedembodiments of the present inventions could comprise the pixelelectrodes made of transparent material, reflective material, orcombinations thereof. The fourth sub-pixels mentioned in the fourthembodiment could be selectively incorporated in the pixel structure, andthe pixel electrodes of the fourth sub-pixels could be made oftransparent material, reflective material, or combinations thereof.

In the above-mentioned embodiments, although the metal layer and theblack matrix are respectively formed on the first and second substrates,but not-limited it in those embodiments. The metal layer and the blackmatrix can be simultaneously formed on the first and second substratesto reduce the effect of light leakage. In other words, the black matrixformed on the second substrate and the metal layer formed on the firstsubstrate is also applicable. Besides, the black matrix could be made ofmetal (such as titanium, aluminum, chromium, tantalum, gold, silver,copper, iron, neodymium, molybdenum, and the likes), alloy, metal oxide,metal nitride, or the composition comprising metal, or polymers (such asblack photoresist, polyester, and the likes), or combinations thereof.If organic photoresist is selected as the material to form the blackmatrix, at least one of the black photoresist and part of the colorphotoresists (such as at least two color photoresists are overlappedeach other), forms on the predetermined position of the black matrix. Ifmetal is selected as the material for forming the black matrix of thepresent invention, the metal layer is patterned to form the black matrixat the predetermined position. If both of the organic material and metalare used for forming the black matrix of the present invention, theorganic material layer could be formed above or under the metal layer.Besides, the sub-pixels are not limited in the rectangular or squareshape, as illustrated in the above-mentioned embodiments of the presentinvention. The shapes of sub-pixels could be polygonal, such as rhombic,hexagonal, pentagon, trapeziform, or the others. Also, the shapes of theslits are not limited herein, and the shapes of the slits such assubstantial branches, comb, substantial fish-bones, V-letter, W-letter,X-letter, the like, or a combination thereof. Furthermore, the storagecapacitor of the above-mentioned embodiments of the present inventionincludes the common electrode and a portion of the second metal layer.However, the storage capacitor could be constructed by the first metallayer and/or the second metal layer and a portion of pixel electrode.Additionally, the protrusions of the above-mentioned embodiments of thepresent invention are formed on the transparent electrode of the firstsubstrate structure (as shown in FIG. 4A, FIG. 4B, FIG. 10A, FIG. 10B),however, the protrusions could be formed on the alignment film. Also,the positions of the alignment controlling patterns, including at leastone of slit and protrusion, are not limited as the illustration in theabove-mentioned embodiments of the present invention. The protrusionscould be formed on the second substrate (upper) structure or the firstsubstrate structure. The slits could be formed on the first substrate(lower) structure or the second substrate structure. If the alignmentcontrolling patterns in the application includes the protrusions and theslits, the protrusions and the slits could be respectively formed on thesecond and first substrates (i.e. opposite to the illustration of FIG.10A) or the protrusions and the slits could be simultaneously formed onat least one of the second and first substrate. Besides, all of thealignment controlling patterns or portion of the alignment controllingpatterns formed on the first and second substrates could be theprotrusions only or slits only.

The above-description is a detailed illustration for a variety ofpreferred embodiments of the present invention. The embodiments shouldnot be construed as limiting the scope of the present invention. Rather,it is intended to cover various modifications and similar arrangementsincluded within the spirit and scope of the appended claims, the scopeof which should be accorded the broadest interpretation so as toencompass all such modifications and similar structure.

1. A method for manufacturing a pixel structure of a display including afirst substrate, a second substrate, and a liquid crystal (LC) layerdisposed therebetween, and the method comprising: forming a plurality offirst, second, and third sub-pixels; forming a plurality of alignmentcontrolling patterns in the first, second, and third sub-pixels; forminga plurality of opaque regions in the first, second, and third sub-pixelsand substantially aligned with at least a portion of the alignmentcontrolling patterns, so that the opaque regions are substantiallyoverlapped with the at least a portion of the alignment controllingpatterns and area percentages of the alignment controlling patternsshielded by the opaque regions in at least two of the sub-pixels aresubstantially different from each other.
 2. The method according toclaim 1, further comprising forming a plurality of fourth sub-pixels, sothat the alignment controlling patterns are formed in the fourthsub-pixels.
 3. The method according to claim 2, wherein eachcorresponding opaque region substantially surrounds each fourthsub-pixel.
 4. A method for manufacturing a display, comprising:providing a first substrate structure and a second substrate structure;forming a plurality of first, second, and third sub-pixels on the firstsubstrate structure and the second substrate structure; forming aplurality of alignment controlling patterns in the first, second, andthird sub-pixels; forming a plurality of opaque regions in the first,second, and third sub-pixels and substantially aligned with at least aportion of the alignment controlling patterns, so that the opaqueregions are substantially overlapped with the at least a portion of thealignment controlling patterns and area percentages of the alignmentcontrolling patterns shielded by the opaque regions in at least two ofthe sub-pixels are substantially different from each other; andassembling a liquid crystal (LC) layer between the first substratestructure and the second substrate structure.
 5. The method according toclaim 4, wherein the alignment controlling patterns comprise a pluralityof protrusions, formed in the first substrate structure in the first,second, and third sub-pixels.
 6. The method according to claim 4,wherein the alignment controlling patterns comprise a plurality ofslits, formed in the second substrate structure in the first, second,and third sub-pixels.
 7. The method according to claim 4, wherein thealignment controlling patterns comprises: a plurality of protrusions,formed in the first substrate structure in the first, second, and thirdsub-pixels; and a plurality of slits, formed at a pixel electrode of thesecond substrate structure in the first, second, and third sub-pixels.8. The method according to claim 4, wherein the display comprises aplurality of black matrixes in the first, second, and third sub-pixels,and the opaque regions comprise at least part of the black matrixes. 9.The method according to claim 4, wherein the display comprises aplurality of metal layers in the first, second, and third sub-pixels,and the opaque regions comprise at least part of the metal layers. 10.The method according to claim 4, further comprising forming a pluralityof fourth sub-pixels, so that the alignment controlling patterns areformed in the fourth sub-pixels.
 11. The method according to claim 10,wherein each corresponding opaque region substantially surrounds eachfourth sub-pixel.